TNF-alpha: a key player in erectile (dys)function. 6. PROJECT SUMMARY/ABSTRACT Current and emerging clinical research studies suggest that the penile vascular bed is a sensitive indicator of early vascular dysfunction, i.e., ED is an early clinical manifestation of generalized vascular disease and carries an independent risk for cardiovascular events. Tumor necrosis factor-alpha (TNF-), a pro- inflammatory cytokine, is an important contributor to many cardiovascular diseases (hypertension, diabetes and metabolic disorders). TNF- levels are also increased in patients with erectile dysfunction (ED) (with or without cardiovascular disease), but so far no study has addressed the role of TNF- on erectile (dys)function. This project proposes to investigate the effects of TNF- on erectile function and how TNF- leads to hypertension-associated ED. More specifically, we will test the hypothesis that the pro-inflammatory cytokine TNF- increases contractile responses of cavernosal smooth muscle cells and plays a direct role in hypertension-associated ED. Three specific aims are proposed, all providing a definition of the specific mechanisms by which TNF- increases cavernosal contractile responses and leads to eretile dysfunction: Specific aim 1: To test the hypothesis that TNF- enhances the constrictor sensitivity of cavernosal smooth muscle cells, leading to impaired erectile function. Specific aim 2: To test the hypothesis that decreased NO bioavailability and augmented RhoA/Rho kinase signaling provide mechanisms for impaired erectile function associated with increased TNF- levels. Specific aim 3: To test the hypothesis that TNF- plays a major role in ED associated with salt-sensitive hypertension and that TNF- effects are partially mediated by increased ET-1 expression. The proposed studies, integrating physiological, pharmacological, biochemical, molecular and cellular techniques, will help to better understand the effects of TNF- on penile function, as well as the contribution of abnormal TNF- levels to functional vascular changes associated with erectile dysfunction. Identification of causal factors and mechanisms responsible for increased vascular content of TNF- in ED and cardiovascular disease may advance disease treatment. Since cardiovascular diseases and ED are a major public health challenge worldwide and are being fueled mainly by increasing obesity and ageing of the population, our proposal is very much in accordance with the mission of the NIH.